Webservers transmit documents or web content to clients, such as a web browser or a website. The term refers on the one hand to the computer equipped with a corresponding web server program and on the other hand to the software itself.
As a rule, a web server is used on the Internet as a WWW service. However, it can also be used locally or in company networks. The respective documents are therefore available worldwide, locally or in-house according to the intended purpose. The web server computer is also called the host. Such a host can process several server programs. The web server or the integrated software is primarily responsible for the reliable delivery of static – for example immutable HTML files and image files – as well as dynamic files.
Dynamic files are pages in which the content is created individually by a logged-in user. As a rule, the webserver transfers the respective HTML page as well as the linked image files (JPG, GIF, PNG, SVG) and design descriptions (CSS) as individual files. Due to this constellation, several hundred inquiries and corresponding server responses are sometimes required to display a complex website. Each web server is able to deliver the website or the content to many different computers at the same time.
This is how the transfer works in detail
The web server program communicates with a web client for transmission. In most cases, the clients are web browsers or search engine crawlers. In the beginning, the web server receives a user request from the browser. In response, the webserver sends an HTML page back, for example. How quickly these delivery works depends above all on the structure and complexity of the respective content. Static web content is often available more quickly because dynamic web content generally requires far more resources.
If it is a static document, it is usually stored directly on the host. In contrast, dynamic content must first be generated, whereby the webserver must execute a program code – for example in Java or PHP – before the actual response. The response from the webserver is then interpreted by the browser or the client. This interpretation means that further requests from the client are often sent to the webserver. The inquiries refer, for example, to CSS files or to embedded images.
Which transmission methods are used?
The standardized HTTP transmission protocols and the encrypted HTTPS variant are used to transmit the files and content. These are mostly based on the two network protocols IP (Internet Protocol) and TCP (Transmission Control Protocol); UDP (User Datagram Protocol) is also used less frequently.
The transmission usually runs via port 80 (with HTTP) or via port 443 (with HTTPS). With the SPYDY developed by Google, there is another network protocol, which is however experimental in nature. This complements the HTTP protocol. For example, the HTTP / 2 standard adopted in 2015 is based on SPYDY in many areas.
Conceptual delimitation: web server and web hosting
The two terms web server and web hosting are fundamentally related with regard to the transfer of web content to clients. Web servers are always a fundamental part of web hosting. The two terms are mistakenly used synonymously by inexperienced Internet users. That’s not right. The two terms can be clearly distinguished from one another.
If the web content is saved and made available, it is referred to as web hosting or hosting. The files of a website are stored on a so-called webspace. This is an online storage space for web projects. The webspace thus functions practically as a hard disk on which the respective content is stored. In order for users to be able to access the web content online, the webspace must always be connected to a web server.
Set up and manage a host yourself
This combination of web space and a web server or a host is made available by a hoster. Users have the choice between a self-managed host and a web server managed directly by the web host. Anyone who chooses a self-managed host is also responsible for the setup. A web server program is mandatory for this.
There are now numerous programs on the market that can be used to operate a web server. There are also free versions on the Internet. It is important in this regard that the operating system of the webserver is compatible with the web server software. The majority of server software for web content is based on Unix or Linux (Tomcat, Nginx, Apache etc.), but is also suitable for Windows.
These are the most used web server programs:
Apache webserver
This popular open-source web server software is available free of charge on the Internet. The entire program has a modular structure and is constantly being developed. It runs on almost all operating systems. PHP and other scripting languages can be easily integrated. However, the installation is comparatively complex and complicated. Various program combinations or software packages (XAMPP etc.) with Apache and software for scripting languages or databases simplify the setup considerably. However, the webserver program has lost ground to the competition. Many other web servers now offer shorter response times for data transmission.
Microsoft IIS
Microsoft IIS can only be used on Windows servers. It is a complete software package with several components. HTTP and HTTPS, as well as POP3, SMTP, FTP, WebDAV and other variants, serve as communication protocols. ASP or .NET applications (ASP.NET) can be specifically executed via Microsoft IIS. If the appropriate ISAPI filters are available, PHP and JSP are also possible.
Nginx
The free software not only acts as a pure web server. Rather, the program offers additional features such as a reverse proxy. This significantly reduces the load on the host, which enables faster work.
Definition: Web server with load balancer and API gateway
What is NGINX?
The software NGINX developed by Igor Sysoev includes a web server, email proxy and reverse proxy. It is freely available under a BSD license and, thanks to the resource-saving way of working, is particularly well-suited for websites with high traffic and traffic. Among others, Netflix and WordPress use NGINX.
Apache Tomcat
This web server program comes from the Java environment. The open-source software acts as a web container for server-side web content that is to be generated via Java. Integration into another web server is also possible. The AJP connector is available for this.
Lite Speed Web Server
The web server software is designed for Unix and Linux. The program is available in three different versions. The speed of data transmission depends on the installed version.
Other tasks of a web server
The primary task of a web server is to transfer the web content. Numerous web server programs include other features and functions. Appropriate software, for example, encrypts communication – via HTTPS – between the web client and web server. In addition, user authentication can be carried out for certain areas. In addition, the webserver software often handles the assignment of cookies and the redirection or forwarding of user calls via the rewrite engine. Caching is also often part of the service portfolio.
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